6 pieces of corrugated nuts are made with brass and rubber sleeves, great accessory for your kayak, canoe, boat.< br/> Features: 6 pieces brass nuts with rubber boot. Tightening a threaded screw into the brass nut expands the insert to secure the fastener. Great accessory for kayak, canoe, boat.< br/> /> Features: Material: Rubber + Brass Size: m4/m5/m6(Optional) M4 Dimension: 13*11mm/0.5 * 0.4 inch M5 dimensions: 17 x 14 mm / 0.7 x 0.5 inches M6 dimensions: 21 x 16 mm / 0.8 x 0.6 inches included)